Oversized pistons for SPL - do they exist?

[RustyBucket]

A question for the pros:
Had my block tank cleaned and SURPRISE !!!
Not sure yet what diameter is going to be needed as it turns out #1 cylinder is scored and requires a sleeve.

But who still has oversized pistons and rings for the SPL?

Can a forklift piston be the better way to go ?

Suggestions?

[unklpat]

Dean has them, but you must have severe damage to need re-sleeving. How big do you need? Dean has up to .060 Pat

[spl310]

Dean and JT have them.

[RustyBucket]

Not certain as to what size is needed. How thick or thin can the block wall be bored before it’s a failure ?
I had slant 6 mopar that I had 60 over and you could go 125 without issues. Best motor mopar made

[C.Costine]

Rusty bucket, this is an everyday ho hum occurrence at automotive machine shops. They have resources that they use every day in order to source the pistons and rings. They don't source specific engine manufacturer pistons and rings they source according to dimensions. They will estimate where they will end up after boring and before going ahead with the bore job they will verify the availability of what will be needed. If the availability is not there they will adjust the end point bore to match up with what is available. This is the service that you get at a good automotive machine shop, and the price will in my experience usually be better than mainstream brand parts sources. When my 1600 was bored they went .050 over and the hunt was a little challenging, but what they came up with were desirable domed pistons, at a price lower than standards usually go for.

[redroadster]

R16 or U20 ? Oh R16....its early

How scored .015 only cuts .0075 back in the 70s shops could just knurl the skirt for that

[RustyBucket]

I asked the shop owner if he could ‘s wedge’ the pistons ( which I believe is the same process to swell the pistons) that is not a process that he recommends.

About a 100 years ago when I owned a Rabbit diesel and had to replace tge short block, a local VW dealer sold me a factory remanufacture short block from VW Canada. It came in a wooden box painted green. The pistons skirts were wedged.
Worked like a charm and had no issues with it

[unklpat]

You haven't answered the question of how much overbore you need. Your machine shop would have given you that. Pat

[RustyBucket]

…. Welll , if the machinist who is doing the work had told me, then we’d have something to chat about.
At the moment, IDK .

Cheers

[unklpat]

Let's chat later.... Pat

[Cyclewrks]

Lou M has bored the R16 out to 90mm on some of his "big 2+L" displacement motors, though he does say that the block needs to have the wall thickness checked before hand to make sure the cores had not shifted during the casting process. I have a U20 being done to run 90mm KA pistons currently.

[RustyBucket]

Wow !! Not sure how far you can bore out the block before you have one of strange double-headed piston motors the Honda prototyped in the 1970's


I got word today that the score was not as bad as once thought, and .30 over Pistons will be needed. If locateable.
So that's pretty good new

[JT68]

We build very high quality R16 pistons in any size. and have .030 and .040 over in stock right now-.020 and 3.5" on order. Glad to help you figure out the best approach depending on what you are trying to do. Domed, flattops and hi compression versions available. Eye candy:

https://www.datsunrestorationproducts.com/shop-11

If you bore the block to 90mm, that is the last waltz for that block-so not a great plan unless you consider the engine expendable- if anything goes wrong, you will be looking for a new block and starting a whole new build. 90mm is REALLY pushing it and some blocks will be ruined/fail at that bore. (that has happened already)

KA and VG pistons are particularly poor choices for the r16 due to the short stroke. (They can be forced to work in a U because of the longer stroke, but even then you typically have to deck the block so there are better choices).

KA/VG/H20 pistons also don't really have the correct dome design for R16's either. Our purpose built pistons are a better solution in every regard since they fit correctly and are much better quality than other options.

Give us a pm or a shout anytime if you need help.

Word to the wise, pistons are not a good place to "go cheap", because the results of failure cost way,WAY more than the initial cost of high quality pistons.